144 On Ceiiain Cavities in Qiiart:^^ Sf^C, 



careous spar for its disintegration by reducing it to quickliftie, 

 between which and water a new chemical combination occurs, 

 which effects its final dissipation, and leaves the specimen as we 

 find it, free from any traces of carbonate of lime, except the mere 

 correspondence of the crystals of the latter with the cavities of 

 the former. ~j 



The crystallized hexagonal surfaces of two of the specimens 

 can be explained by either the agency of heat or water, as crys- 

 tallization from solution can be artificially effected by evaporation, 

 and afterwards can be again liquefied by heat, and re-crystallized 

 by gradual cooling. Yet the specimen containing actynolite 

 would indicate an igneous origin. 



Whether the formation of these specimens can be attributed to 

 either of the above causes, or to both, or to neither of them, and 

 at what particular geological period they may have occurred my 

 knowledge is too limited positively to determine. Their conside- 

 ration, too, may be more curious than useful, yet as they have not 

 received any attention from the authors in my possession, I have 

 taken it for granted that the specimens are rare, and that Iheir 

 history might be a slight contribution to science. These motives 

 have induced me to forward you an account of them, with my 

 hasty views of their production, believing, too, that if they pos- 

 sessed real interest my communication would not be unwelcome, 

 and that if they do not, no harm could result. 



P. S. There is a communication on Spontaneous Combustion 

 in Vol. XXXIII of your Journal, by Dr. James Mease, and among 

 other instances is one taken from Hazard's Register of Pennsyl- 

 vania, of a piece of >vood taking fire in the store of Mr. Adam 

 Reigart of our city. This statement differs from that made to me 

 by Mr. Reigart and his clerk, Mr. G. H. Whitaker. The wood 

 was chestnut^ quite solid, about eight inches long, and three or four 

 wide, and cut smooth with a penknife. Two days before the 

 burned wood was observed, they had washed the shelf and han- 

 dled the wood with loet hands. When first noticed it was not 

 then on fir^e, but the most of it had been reduced to ashes. The 

 unconsumed portion was ragged and perforated,* and what is 

 remarkable, not in the least cliarred, while the paint on the shelf 

 on which it lay was destroyed as by fire. Mr. Whitaker still had 

 a portion of the wood and ashes, which he presented to me. ^ 



■* Probably the combustion only took place at the points which had previously 

 been wet. 



